The present invention relates to a method for imparting an ability of preventing obesity and impaired glucose tolerance to foods, and a food and a sugar preparation exhibiting such preventive effects.
Recently, eating habits have been improved, but the population of patients suffering from geriatric diseases represented by obesity and diabetes increases steadily because of hypernutrition and unbalanced diet as well as lack of exercise. Under such social background, there have been developed various agents for inhibiting an increase in the blood-sugar level and excess insulin-secretion for preventing healthy person from suffering from obesity and/or diabetes or for treating patients requiring the control of the blood-sugar level such as those suffering from diabetes. As such agents, there have been known, for instance, Acarbose (available from Bayer Yakuhin, Ltd.) and A0-128 (available from Takeda Chemical Industries, Ltd.) which are substances having an effect of inhibiting the gastrointestinal absorption of sugar and starch and inhibitors for enzymes involved in digestion, but both of them are medicines and the ingestion or intake thereof for the preventive purpose becomes a cause of various problems. For instance, they suffer from a problem of safety, since they would be dangerous because of possible side-effects. Moreover, polymers of glucose moieties bonded through .alpha.-1,6-bonds such as isomaltotriose, dextran and pullulan have been known to have an effect of inhibiting an increase in the blood-sugar level in response to ingestion of sugar. Isomaltotriose and dextran as such are digested and absorbed and, in particular, dextran suffers from a problem of safety since it has been proved that dextran exhibits side-effects such as an effect of elongating the blood-coagulation time. On the other hand, pullulan can inhibit any increase in the blood-sugar level after the ingestion of sugar, but is substantially ineffective for the control of the blood-sugar level after the ingestion of glucose and maltose. Moreover, the effect thereof for controlling the insulin-secretion has not yet been proved. Furthermore, pullulan has been known to control an increase in the body weight when it is administered to a young rat and to inhibit the growth thereof.
On the other hand, the effect of insulin is very important for controlling the sugar-metabolism in patients suffering from diabetes, persons whose probability of suffering from diabetes is high or patients suffering from obesity and, therefore, it is needed for these persons or patients to protect, hold and/or enhance the effect of insulin. There have been used, for instance, solutions for transfusion and foods containing monosaccharides or sugar alcohols such as fructose, sorbitol and xylitol; disaccharides and their alcohols such as maltitol, maltose and leucrose; and glucose polymers (U.S. Pat. No. 3,928,135), capable of being digested in and absorbed by living bodies independent of the effect of insulin, for the prevention of temporal hyperglycemia after the ingestion of these sugars, for saving the insulin-secretion, for the supplementation of energy or for controlling the osmotic pressure of transfusion solutions. However, these mono- and poly-saccharides and their alcohols have high degrees of sweetness, but the quality of sweetness thereof is inferior to that of sugar. In addition, sugar alcohols often becomes a cause of diarrhea. Moreover, it has been known that the glucose polymers do not stimulate any insulin-secretion when it is used in the form of a transfusion solution, but the transfusion is a medical act and cannot be commonly adopted.
Some dextrins have also been used for the same purpose explained above and examples thereof include pyrodextrin, white dextrin and yellow dextrin. The pyrodextrin is generally prepared by heating a starch having a moisture content of several percentage in the presence or absence of an acid. The conditions for heating are a temperature ranging from 135.degree. to 218.degree. C. and a heating time ranging from 10 to 20 hours for British Gum which is obtained by roasting without using any acid. On the other hand, the white dextrin is prepared through the heat-treatment performed at a temperature ranging from 79.degree. to 121.degree. C. for 3 to 8 hours in the presence of an acid. Further the yellow dextrin is likewise prepared through the heat-treatment performed at a temperature ranging from 150.degree. to 220.degree. C. for 6 to 18 hours in the presence of an acid.
Sugar preparations are in general prepared by mixing sugar with other ingredients, but when the sugar preparations are subjected to domestic use in the form of table sugar like sugar for home use, various problems arise. For instance, they have poor flow properties, aggregated into massive coarse particles due to moisture absorption. In addition, they are separated into individual ingredients upon being packaged in a container and thus become non-uniform since the particle size and specific gravity of sugar differ from those of other ingredients used.